1. Field of the Invention
This invention relates to an emitter such as an electroluminescence (also referred to hereunder as EL) element and the like, which is suitable for a display body or a light source, a method of designing the brightness and a program for designing the brightness of this emitter, and furthermore an electrooptical device and an electric device.
2. Background Art
Heretofore, a range of emitters such as a display body, a light source and the like using EL elements (especially, organic EL elements), being spontaneous light emitting diodes, has been proposed (for example, refer to Japanese Unexamined Patent Application, First Publication No. 10-12377 (Patent Reference 1)). An organic EL device that is capable of color display is also known as one such emitter.
In order to perform color display by an organic EL display device, it is normal to construct one picture element from an organic EL element (emission unit) that eits red, an organic EL element (emission unit) that emits green, and an organic EL element (emission unit) that emits blue, corresponding to red (R), green (G) and blue (B), being the three primary colors of light. For example, in a case where a picture element is required to be bright white, all the organic EL elements of red, green and blue may emit light. Furthermore if the emission brightness of each of the red, green and blue organic EL elements constituting one picture element is controlled appropriately, it is possible to adjust a required picture element to a desired color and brightness.
In the case where color display is performed using three organic EL elements as described above, it is known to be important to create good white balance (for example, refer to Japanese Unexamined Patent Application No. 2000-353590 (Patent Reference 2).
Accordingly, heretofore, when considering the emission brightness of the three EL elements constituting each picture element, an emission area (emission area capable of irradiating light externally) that enables a good white balance to be obtained has been determined for each of the colors, and a numerical aperture has been determined for each of the organic EL elements so as to obtain the emission area.
However, in the conventional method of obtaining numerical apertures as described above, the emission brightnesses of the organic EL elements can provide a good white balance immediately after the products are shipped. However, since different emission materials normally deteriorate differently, white balance is lost after a certain time has elapsed after first use (after the cumulative emission time reaches a certain time). Therefore there are unsolved problems in that even if a prescribed current is supplied to each organic EL element with a goal of white emission, the actual color development is not pure white, and even if another required color is intended to be developed to a required brightness, the intended color development state cannot be obtained.
The present invention addresses these unsolved problems in the conventional technique, with an object of providing an emitter comprising a plurality of types of emission units (for example, EL elements) with different emission aging characteristics, which can obtain good emission conditions even after a certain usage time has elapsed, and furthermore a method of designing the brightness and a program for designing the brightness of the emitter, an electrooptical device and an electric device.